Preparative electrofocusing procedures have been used to purify proteins of isoelectric points of 4.90, 5.33, 5.58, 6.00 and 6.10 from mixed saliva of a caries-inactive donor and which have been established to be among the 8 proteins selectively hydrolysed by Strep. mutans. Proteins of isoelectric points 4.90, 5.33 and 5.72 also have been purified from submandibular saliva of caries-active donors. The chemical properties of these proteins are currently being characterized. Also, proteins of similar electrophoretic characteristics to those listed above, but which are refractory to microbial attack, will be purified from submandibular saliva of caries-free donors. The proteins purified from submandibular saliva of caries-active and caries-free donors will be compared. Recently 4 proteins with isoelectric points of 4.70, 4.90, 4.98, and 5.05 have been purified from mixed saliva of a caries-free donor. Each of these proteins has been found to inhibit growth of strep. mutans or Strep. sanguis. The properties of these proteins will be compared to proteins of similar electrophoretic characteristics from saliva of caries-active donors. These studies also will include the identification of the glandular source of the growth-inhibitory proteins.